Diaphragm switch



Fb. 22, 1938. vP. M. FARMER ET AL I 2,109,145

DIAPHRAGM SWITCH Filed June 28, 19:55

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. F @72:75 @Evang 'Ey ATTORNEY.

Patented Feb. 22,\ 1938 UNITED STATES PATENT OFFICE DIAPHBAGM SWITCH Jersey Application June 28, 1935, Serial No. 28.858

8Claims.

The present invention relates to an improvement in air actuated diaphragm switches especially for those used in the so called aero-tube ire alarm systems, in which the rise and fall of air pressure in the tubes is automatically varied in accord with the room temperature changes in which the system is installed.

One of the main advantages gained by the present structure is through the use of duplex, concentrically convoluted, thin, metallic diaphragms, preferably of a suitable light metal such as aluminum, whereby greater sensitivity to air pressure fluctuations is obtained, and, due to the mode of attaching the diaphragms to join them at their perimeters, there is no tendency of drawingthe natural spring temper of the diaphragms as when soldered, and thus all diaphragms of given diameter, are all alike in operative characteristics and of uniform structure and results.

Further, due to the present method of assembling the components of an instrument as herein outlined the two diaphragms are connected into operative assembly with themselves and their cooperating appurtenant parts, which prevent the diaphragms from becoming distorted and from being given undesired internal stresses.

Another feature of advantage is accomplished by the manner in which the diaphragms are peripherally connected, this mode of fastening having two functions, one, to seal the diaphragms in uniform edge contact and the other, to'act as an inertia member to prevent thel delicately mounted diaphragms from chattering, and thereby cause false alarms.`

The foregoing, and other features of advantage will be apprehended as the herein description proceeds, and it is obvious that modifications may be made in the structure herein, without departing from the spirit hereof or the scope of the appended claims.

In the drawing,

Fig. l is a transverse sectional view of the present diaphragm construction, enlarged over lifesize to better show the details thereof, this diaphragm structure as viewed from the top, being round, as is customary in this type of device; and

Figs. 2, 3, 4 and 5, are enlarged, fragmentary sections of modified rim assemblies showing the manner in which the diaphragm discs are bound together in operative assembly. I

As in Fig. l, the complete structure comprises two substantially similar diaphragm discs I and 2, these preferably being concentricaliy convoluted, can be made from the same dies, in manu,-

(CL 20G-83) 'I'he bushing I Il is bored as at Il, and commu` nicates between the interior of the spaced diaphragms and the bore i9 of the threaded coupling D, said spud I Il being press-tted into said bore I9.

The lower diaphragm 2, is, by means of the edge of its central bore, seated upon the taper face 2| of coupling D, and then a ductile lead washer I3 is overlaid upon the diaphragm with its bore in registry with the bore 22 in coupling D, and the bushing I0, with its taper faced flange i2 is tightly pressed down to a seat, thus compressively holding diaphragm 2 in its desired operative position in an air-tight manner.

The coupling D, on its top face, is provided with an upstanding circular shoulder 2i, which receives thereon a bored circular guard plate 20, which is press-fitted upon said shoulder 2i, to guard the exposed face of diaphragm 2 against injury. 'I'his guard plate is positioned adjacent diaphragm 2, but is spaced far enough distant therefrom so as not to interfere with the action of said diaphragm. The coupling D at its upper end I5 is of cylindrical cross-section, and immediately below this cylindrical section is a hexagonal portion I4 and il, bifurcated by a groove I6, and the lower end ofthe coupling is provided with a reduced threaded end i8.

The hexagonal portion il-I'l is used to permit the use of a wrench when fitting the device in operative position.

The groove I6 is provided for the purpose of holding the completed instrument, by means of a forked yoke, not shown, in said groove in the seat of a special testing device, in which there are no threads, so that the threaded end i8 is not used to lock the diaphragm in the testing machine, but the yoke is used to rapidly hold and release diaphragms during the inspection and testing thereof at the factory.

'Ihe two circular diaphragms, or discs i and 2, as in Figs. l and 2, are firmly clamped together at their peripheral edges by an outer double flanged annulus comprised of two outer clamp- -ing flanges 4 and l which are, preferably integral with the outer rim portion B.

In assembling the discs, and after having assembled disc 2, as previously described, to coupling D, a compressive washer l is placed upon iiangel l, and this is done before the closing down of the top ange I, this being indicated by the dot and dash lines E, Fig. 1.

Then the ring, with washer l therein is brought up around the edges of disc 2, then another compressible washer 9 is placed upon the top face of disc 2, then the top disc I is dropped into the clamp ring upon the washer 9 and finally a compressible washer 1 is placed upon the disc I and the flange 4 clamped down upon the assembly, as in Fig. 2, compressively effecting an air tight assembly of the peripheral edges of the discs I and 2.

In Fig. 3, the assembly is substantially the same as that described for Figs. 1 and 2 except that the inner washer 8 is not used, and the two peripheral edges of the discs I and 2 are contacted as at A, and the sealing eifected by the washers 1 and 0 only.

In Fig. 4 the central washer l only is used with the discs I and 2 separated, and thus an effective seal is created when the clamp ring is finally closed down directly over the two dises.

In Fig. 5 there is shown a modined form of disc assembly in lwhich the lower disc, as viewed in said Fig. 5 is of sufficiently larger diameter than disc I, to provide for an integral clamp ring portion 4 5-6. Washers 1 and 8 are used and thev central packing washer 9\ is not used bringing the contacting edge of disc I between washers 1 and 8, as at B. Further, the

metal so as to further add to the weight of the perimeter of the diaphragm. andv thus act as a 4o' circumferential balance and vibration dampener,

without loss of efliciency. Y

The upper diaphragm I, at its center is provided with a riveted on electrical contact point ZIhaving a platinum facing 3, which may be welded to the surface of the contact point. This point may be provided with a riveting teat or extension 24, which extends through a centrally located rivet hole in disc I, Fig. 1, and through the bore of a rivet washer 25, and is then riveted over the said rivet washer 25. This form of construction further adds to means for the prevention of inner strains and distortion of the disc, as the riveting strain is taken up directly by the rivet washer.

'I'he points of advantage of the foregoing construction are, irregular annealing of the discs I and 2 is eliminated because they are mechanically locked or clamped together, and are not soldered, therefore the metal of the discs when stamped, convoluted and assembled uniformly retain their natural resilience.

The method of assembly further prevents distortion as the parts are struck together in a closing die thereby obtaining multiple assemblies which are, substantially all uniform in action and structure.

It is possible in varying sized diaphragms for different duties to counterweight the perimeters thereof for dampening the different natural oscillatory periods, and thus obtain a more satisfactory action when in an aero-tube circuit.

In one :form of use these diaphragms may be connected to an aero-circuit as above described and connected into an open, re alarm, electric circuit with the open contact of the electrl Gil'- cuitlocated adjacent the contact member 22 on disc I, but not in electrical contact therewith. Normal surgings of the discs I and 2 will therefore not send nre alarms, but a sudden, sustained rise of pressure in the aero-system will cause the discs I and 2 to expand, to an extent that will close contact 22 said open circuit contact and cause the electric circuit, of which the diaphragm is a part, to send an alarm, in the customary manner.

As thus constructed it will be seen that the diaphragm discs are suspended upon the coupling D, for free action. The coupling being anchored solidly in operative position holds the two assembled resilient dises in free suspension through their compounded resilient connection by reason of the weighted connected perimeters and the attachment of the lower disc 2 to the coupling.

Having thus described the invention what is claimed is:

1. 'I'he combination of a metallic air operated apparatus comprising a pair of diaphragms having outer boundary margins, a washer disposed between said margins to provide a space between the diaphragms, one of said diaphragms having therein an opening, 4and there being a tubular coupling communicating with said space through the opening, said coupling including a pair of members which embrace the associated dia- Dhragm around the margin of the opening; clamping means including another washer, and means integral with one of said margins and extending therefrom, said second means having a flange extending inwardly over the second mentioned washer, and an inner stiii'ening edge portion on said flange, said portion being engaged against the associated washer at the inner circumferential face thereof.

2. An air-pressure-operated device for airexpansion-tube alarm systems, said device comprising a coupling having a bore and a dared inclined seat around the bore; an inner diaphragm having intra-marginal annular corrugations thereon, a central opening and a tapered portion around said opening tightly fitting said seat and forming a recess; a tubular bushingin said bore and carrying a heavy strong flared flange clamping against said tapered portion and 4disposed approximately within said recess; an outer corrugated diaphragm over the inner diaphragm; means securing the margins of the diaphragms airtightly together; and a contact carried on the central portion of the outer diaphragm; said flaring seat and ange having the new functions of disposing the flange approximately entirely between the inner and outer planes of the inner diaphragm, thus economizing space and allowing small volume between the diaphragms, thereby promoting sensitivity; said flange and seat having the further function of engaging the dia- Phragm with a wedging force, thereby increasing the air-tightness 'of the fit, and the further function of bracing the diaphragm at the seat.

3. An air-pressure-operated device comprising a coupling having a bore and an outwardly flared inclined seat around the bore; an inner diaphragm having intra-marginal annular corrugations thereon, a fiat outer margin, a central opening and a tapered portion around said opening fitting said seat and merging into the adjacent corrugation; a tapered lead washer fitted on said tapering portion; a tubular bushing fcrceouter planes'V of the diaphragm substantially flush with the top face of the corrugations of the inner diaphragm-and clamping said seat, washer, diaphragm and flange air-tightly together; an outer diaphragm disposed over the inner diaphragm and having a flat central portion, annular corrugations therearound, and an outer at margin; means securing said margins airtightly together; and a contact carried on said central portion; the flaring seat and flange having the new functions of disposing the flange approxi: mately entirely between the inner and outer planes of the inner diaphragm, ecornizing space, allowing small volume between the diaphragms, promoting sensitivity; said flange and seat having the further function of engaging the diaphragm and washer with a wedging force, thereby increasing the air-tightness of the fit, said tapering diaphragm portion having the further function of bracing the diaphragm at the seat to prevent portions thereof .from buckling when the diaphragm is flexed.

4. An air-pressure-operated device for air-expansion-tube alarm systems, said device comprising a seat; an inner diaphragm having intramarginal annular corrugations thereon, a flat outer margin, a mid-portion mounted on said seat; an outer diaphragm disposed over the inner diaphragm -and having flat central portion, and outer margin and corrugations therebetween; compressi-ble packing washers on both sides of said margin of one ofthe diaphragms the other diaphragm being formed into a flange extending over said washers to the inner edge of one of the washers; and an electric-switch contact carried on the outer face of said central portion; said diaphragms being verylight, thin, delicate and highly elastic and havingv a natural oscillation frequency and easily set in oscillation; the weight ofthe washers being predetermined and selected relative to the weight and frequency of the diaphragms to neutralize and damp said oscillation, thus forming a floating non-frictional damping means.

5. An air-pressure-operated device for air-expansion-tube alarm systems, said device comprising a coupling having a bore and a seat around the bore; an inner diaphragm having intra marginal annular corrugations thereon, a flat outer margin, a central opening and a portion around the opening mounted on said seat; an outer diaphragm disposed over the inner diaphragm and having fiat central portion, and outer flat margin and corrugations therebetween; compressible washers against the outer faces of said margins; a metal washer between the margins; a double flanged annulus clamping said washers and margins together; and an electric-switch contact carried on the outer face of said central portion;

said diaphragms being very light, thin, delicate,

highly elastic and vibratory, and having a natural oscillation frequency easily set in oscillation by usual extraneous vibrations to cause chattering; the combined weights of said Washers and g annulus being predetermined and selected relative to the weight and frequency by the diaphragms to neutralize and damp said oscillations, thereby to prevent said chattering; said margins being free of holes or solder whereby inertia, at the margins, and the elasticity of the diaphragms are uniform; the metal washer having the additional function of providing stiffness to said margins.

6. An air-pressure-operated device for air-expansion-tube alarm systems, said device comprising a coupling having a bore and a seat around the bore; and inner diaphragm having intramarginal annular corrugations thereon, a flat outer margin, a central opening and a portion around the opening mounted in press iltted relation on said seat; an outer diaphragm disposed over the inner diaphragm and having flat central portion, and an outer flat margin and corrugations therebetween; a, metal washer be-.

tween said margins; a double-flanged annulus clamping said margins and washer airtightly together; and an electric-switch contact carried on the outer face of said central portion; said diaphragms being light, thin, delicate and highly elastic; said margins being free of holes or solder whereby inertia, at the margins, and the elasticity of the diaphragms are uniform.

'7. ,An air-pressure-operated device comprising a coupling having a ybore and an outwardly flared inclined seat around the bore; an inner diaphragm having intramarginal annular corrugations thereon, a central opening and a tapered portion around said opening fitting said seat and merging into the adjacent corrugation; a soft Washer fitted on said tapering portion; a bushing secured in said bore and having a flared flange clamping said washer tightly on said tapered portion; an outer diaphragm disposed over the inner diaphragm; and means securing the margins of the diaphragms airtightly together; said flange and seat having the function of engaging the diaphragm and soft washer with a wedging force, thereby increasing the air-tightness of the fit, and the further function of bracing the diaphragm at the seat to prevent portions thereof from buckling when the diaphragm is flexed.

8. An air-pressure-operated device for air-expansion-tube alarm systems, said device comprising a coupling having a bore and a flared inclined seat around the bore; an inner diaphragm having intra-marginal annular corrugations thereon, a central opening and a tapered portion around said opening tightly fitting said seat and forming a recess; a tubular bushing in said bore and carrying a heavy strong flared flange clamping against said tapered portion and disposed approximately with said recess; an outer corrugated diaphragm over the inner diaphragm; means securing the margins of the vdiaphragms airtightly together; and a contact carried on the central portion of the outer diaphragm; said flaring seat and flange having the new functions of disposing the flange approximately entirely.

between the inner and outer planes of the inner diaphragm, thus economizing space and allowing small volume between the dlaphragms, thereby promoting sensitivity.

PAUL M. FARMER. FRANCIS C. EVANS. 

